PROBLEM:
Evaluate $$\left(\frac{\displaystyle\sum_{n=-\infty}^{\infty}\frac{1}{1+n^2}}{\operatorname{coth}(\pi)}\right)^2$$
CONTEXT:
I saw a very interesting and yet intimidating question on the internet:
Find the value of $$\frac{16\displaystyle\int_0^\pi\int_0^1x^2\cdot\operatorname{sin}(y)\:\:dxdy\:\:\left(\frac{\displaystyle\sum_{n=-\infty}^{\infty}\frac{1}{1+n^2}}{\operatorname{coth}(\pi)}\right)^2}{\displaystyle\sum_{n=1}^{\infty}\frac{1}{n^2}}+5$$
I just know or rather heard that (though I don't know the proof) $$\sum_{n=1}^{\infty}\frac{1}{n^2}=\frac{{\pi}^2}{6}$$ and (I calculated it) $$16\displaystyle\int_0^\pi\int_0^1x^2\cdot\operatorname{sin}(y)\:\:dxdy=\frac{32}{3}$$ but I can't calculate the value of the expression written in the big brackets.
Any help is greatly appreciated.